1. Technical Field
The present application relates generally to nanotube films, layers, and fabrics.
2. Discussion of Related Art
Resonators are useful in signal processing systems as well as other systems. Reduction in the size of a resonator enhances its resonant frequency and reduces its energy consumption. When used as sensors, higher resonant frequency can translate into heightened sensitivity. When used in wireless communications, higher frequency resonators enable higher frequency filters, oscillators, and mixers to be made.
Current state of the art technology utilizes on-chip MEMs resonators. The motivation of MEMs technology in wireless communications is as a replacement for off-chip bandpass filters constructed from relatively large quartz resonators. MEMs resonator technology entails the fabrication of suspended silicon structures that are manipulated by applying an electric field to the structure, causing the suspended beam to vibrate at a specific frequency. These suspended silicon structures are typically several microns in length, width and height and have demonstrated frequencies greater than several MHz. Such suspended, mechanically active structures allow applications in force microscopy, optical couplers, and stable oscillators and filters.
Individual bridged carbon nanotubes have been used in resonator systems. See Li., C. et al., “Single-walled carbon nanotubes as ultrahigh frequency nanomechanical resonators”, Phys. Rev. B, 2003, Vol. 68, pp. 073405-1-073405-3, the entire contents of which are incorporated herein by reference. Other materials that are being investigated for use in micro- or nano-sized actuators include: aluminum nitride, silicon (both single crystal and polycrystalline), silicon nitride, gallium arsenide, and silicon carbide. Mechanical actuation and sensing in most of these materials relies on electrostatic, optical, or magnetomotive techniques, which suffer from poor coupling and implementation difficulties. The use of aluminum nitride allows for high resonance frequencies and piezoelectric actuation. See Cleland, A. N., et al, “Single-crystal aluminum nitride nanomechanical resonators”, Appl. Phys. Lett. 2001 Vol. 79, No. 13, 2070-2072, the entire contents of which are incorporated herein by reference. There has been a growing requirement for smaller, cheaper, lower power and higher performing resonators for application in wireless communications and other applications.